1. Field of the Invention
The present invention relates to a method of forming a layer on a semiconductor substrate and an apparatus for performing the same. More particularly, the present invention relates to a method of forming a layer using an atomic layer deposition (ALD) method followed by a chemical vapor deposition (CVD) method in the same processing chamber and an apparatus for performing the same.
2. Description of the Related Art
Modern semiconductors use extremely small metal wiring. Whereas in the past aluminum (Al) has been the material of choice for such wiring due to its low specific resistance and ease of use in processing, extremely dense circuits owing to better manufacturing techniques require better conductor materials. Copper (Cu) has a much lower resistance and higher yield strength than aluminum and is thus much desired for use in semiconductor wiring. Unfortunately, copper has a major drawback in that copper atoms tend to diffuse into the silicon of the semiconductor substrate, thus affecting the performance of the semiconductor device. Additionally, copper is more difficult to dry-etch than aluminum and is difficult to adhere to other materials, thereby presenting an uneven surface between the copper and a contiguous material.
For those reasons, the copper wiring requires a diffusion barrier layer for preventing diffusion between the copper layer and the semiconductor layer or substrate so as to improve device reliability. One commonly used diffusion barrier layer include titanium nitride (TiN) due to its high strength and good conductivity. The titanium nitride (TiN) layer has also been used as an electrode of a capacitor of a semiconductor device.
However, titanium nitride (TiN) as a diffusion material creates several problems. Most importantly, titanium nitride is difficult to apply to a semiconductor substrate. Application of TiN via physical vapor deposition (PVD) often results in poor step coverage thus making such application method ill suited during highly integrated semiconductor devices. Application of TiN via organic chemical vapor deposition (MOCVD) often includes unintended contaminants such as carbon (C) and oxygen (O) thus requiring a subsequent plasma treatment process to remove the contaminants. Application of TiN via a chemical vapor deposition (CVD) process often results in diffusion of chloride ions (Cl−) from a base reactant gas into an underlying layer, thus resulting in degraded electrical characteristics of the resulting device. Finally, application of TiN via an atomic layer deposition (ALD) is an extremely slow process thereby severely reducing manufacturing productivity.
Accordingly, the need remains for methods for applying a diffusion material onto a substrate that overcomes the drawbacks of the prior art.